To use your micro:bit with the Open Roberta Lab, all you have to do is connect your micro:bit to your computer via USB cable. The micro:bit then logs on to your computer as a USB device and you can simply transfer the programs you created with the Open Roberta Lab to the micro:bit.
If you use the »Show on Serial Monitor ...« block in your program, you want to be able to read the output on your computer. Our Open Roberta Connector has a built-in serial monitor for this purpose. You can read how to use it here.